Railway traffic controlling apparatus



March 24, 1942-. A R, cRooKs 2,277,541

' RAILWAY TRAFFIccoNTRoLLING APPARATUS Filed Feb. s, 1941 Hfen Mqdalazaz Azzplzr v xlep A i .`.C X E 20A? n f i 100% vv l 7mm Cazz'o! man Cafnpdm ZgJ. Egal/'Umani Z6 VT Tobca Pilar@ of Ib l HIS ATTCRNEY Patented Mar. 24, 1942 RAILWAY TRAFFIC ooN'rnoLLiNG APPARATUS Ralph K. Crooks, Sharpsburg, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application February 8, 1941, Serial No. 377,964

9 Claims. (Cl. 246-63) My invention relates to railway traffic controlling apparatus, and more particularly to train carried train control equipment responsive to alternating current.

Train carried train control equipment re sponsive to alternating current has been largely standardized for use with alternating current supplied either to a series rail circuit and to a loop rail circuit including the rails in multiple and a return line wire, or to a series rail circuit only and coded by being periodically interrupted at diierent code rates. In the rst arrangement the phase relationship of the currents inthe two circuits produce different conditions of the. train control equipment, and in the second arrangement the code rates provide dierent conditions of the associated train control equipment. The alternating current is preferably of 100 cycles per second in order to be free from interference with alternating current of commercial power lines. Irain carried receivers or inductors are mounted on the train in inductive relation to the track rails and the energy thus picked up is applied to the associated train control equipment which includes an amplier for operating a control relay connected tothe output of the amplier. In the first form of equipment the control relay is a two winding three position alternating current relay, which is biased to a mid position, is operated to one extreme position when the currents supplied to the two windings are in phase and is operated to the other extreme position when the two currents are 180 degrees out of phase. One winding of this relay is energized in response to energy picked up from the series rail circuit and the other winding is energized in response to energy picked up from the loop rail circuit. In the second form of equipment, the control relay is a code following relay which governs decoding means tuned for response to the different code rates at which the relay is operated. f

Track sections of the order of 11,000 feet in length have been proposed for railway signal systems to provide satisfactory train braking distance for high train speeds. Broken rail protection is .an essential function for railway signal systems and effective broken rail protection may not always be obtained for a track circuit of 11,000 feet in length when alternating current of 100 4cycles per secord is used. Alternating current of a relatively low frequency such as, for example, 20 cycles per second has been found to provide effective broken rail protection for track circuits of 11,000 feet. When energy is inductively transferred between the Vtrack rails and train carried inductors, the frequency of the current determines in part the magnitude of the energy transferred.

In View of the above cited standardized train control equipment for signal systems lof the type here involved and the desirability of using relatively long track circuits,y a feature of my invention is the provision of railway traffic controlling `apparatus incorporating novel means wherewith alternating current of a relatively low frequency, such as 20 cycles per second, effectively influences train control equipment of the standardform which is designed for response to alternating current of a relatively high frequency, such as cycles per second.

Another feature of my invention is the provision of railway traffic controlling apparatus incorporating novel means for converting alternating current of a relatively low frequency into alternating current of a relatively high frequency.

Again a feature of my invention is the provision of a novel adapter which when introduced between the present train carried receiver and the standard amplifier associated with train control equipment, the amplifier and the control relay governed thereby are effectively operated in response to a relatively low alternating current notwithstanding the standard equipment is designed for operation by alternating current of a relatively high frequency.

The above features of my invention,.as well as other advantages which will become appa-rent` as the specification progresses, are attained by -providing an adapter comprising an electron The energy passed by the first filter is mixed in f the modulator with locally generated oscillations and the'frequency of the local oscillations is such that one product of modulation is energy of a frequency corresponding to that required for operation of the standard equipment. Amplication of the modulated energy is also effected in the adapter. The second filter of the adapter is interposed between the modulator-amplifier and the output terminals of the adapter and is proportioned to pass only that product of modulation the frequency of which corresponds to that at which the standard equipment responds. The output ter-iinals of the adapter are arranged to be connected to the input terminals of the standard equipment. In the preferred form of apparatus embodying my invention a single multiple grid electron tube functions to produce the l`cal oscillations, modulation of the local oscillations with the incoming energy, and amplification of the modulated energy. Hence such adapter when interposed between the train carried receiver and the standard train control equipment is effective to supply to the standard equipment energy of the frequency for which it is designed in response to alternating current of a different frequency picked up from the rails.

I shall describe two forms of apparatus embodying my invention and shall then point out the novel features thereof in claims.

In the accompanying drawing, Fig. l is a diagrammatic view showing in a conventional ner apparatus embodying my invention. Fig. 2 is a diagrammatic View showing one form of apparatus embodying my invention when used with standard train carried train control equipment responsive to coded alternating current. Fig. 3 is a diagrammatic View showinCr one form of apparatus embodying my invention when used with standard train carried train control equipment responsive to alternating currents picked up from a series and a loop track circuit.

In each of the different views, like reference characters are used to designate similar parts.

Referring to Fig. 1, the reference character IC designates in a conventional manner a train carried receiver of the usual and well-known form and which consists of two inductor coils mounted on the train one over each rail and connected together in such a manner that the electromotive forces received by the two coils are additive in their eifects,

In order to better understand my invention, I shall assume that the track circuits from which energy is picked up by the train carried receiver IC is alternating current of 20 cycles per second, the utility of such 20 cycle current being that effective broken rail protection is obtained for relatively long track circuits and effective transfer of energy between the rails and the train carried receiver is also obtained. It is to be understood, of course, that my invention is not limited to alternating current of 2() cycles and any other preselected relatively `low frequency may be used. Furthermore, it is to be observed that the existing train carried train control equipment is standardized for use with alternating current of 100 cycles per second, or at least to alternating current of the frequency of the order of 100 cycles, but that such train carried equipment may be designed for response to alternating current of some other frequency.

Again looking at Fig. 1, the energy picked up by receiver IC is applied to a filter designated by the reference character A and which lter is proportioned to pass only alternating current of 20 cycles per second. The reference character B designates a local train carried oscillator which is designed to deliver energy at 129 cycles per second as indicated in the drawing. The energy passed by filter A and the energy delivered by oscillator B are mixed at a modulator C. One of the products of modulation is energy of the frequency equal to the diiference between that passed by lter A and that delivered by oscillator B and in the instant case is energy having a frequency of cycles per second (120 minus 20). This product of modulation along with the other products of modulation are amplified by an ampliiier designated by the reference character D. A lter designated E is interposed between the amplifier D and the input termina-ls of the existing standard train control equipment and filter E is proportioned to pass only energy of 100 cycles per second. That is, filter E passes only the one product of modulation equal to the difference between the oscillations delivered by oscillator B and the energy passed by filter A, and the other products of modulation are suppressed. I-Ience, with the existing standard train control equipment connected to the output terminals of filter E, such train control equipment is supplied with energy of the frequency to which it is designed in response to a relatively low frequency energy derived from the track circuit.

Referring to Fig. 2, the inductor coils 2 and 3 are mounted on a train in inductive relation to rails ia and lb, respectively. The track rails la and ib are supplied with 2O cycle alternating current from a source not shown and which current is coded at dierent code rates according to different tramo conditions. The means for supplying coded alternating current to rails la and ib isimmaterial and is not shown in order to simplify the drawing, since it forms no part of my invention and is not required for a full understanding of the apparatus embodying my invention. The means for supplying coded alternating current to the rails ia and ib may be any one of the forms in present day use, and, for example, may be that covered in Letters Patent of thc United States No. 1,986,679, granted January 1, i935, to L. V. Lewis for Railway trafc controlling apparatus. In accordance with usual practice, the inductors 2 and 3 are connected together so that electromotive forces induced therein during each on period of the coded rail current add their effects. The inductors 2 and 3 are connected to the input terminals i and 5 of an adapter designated as a whole by the reference character AD, and which adapter embodies devices correspondinsr to devices A, B, C, D and E of Fig. 1.

The lter or adapter AD, which corresponds to filter A of Fig. l, comprises primary and secondary windings S and l' of a transformer Ti and two condens-ers 8 and 9, and this filter is connected to input terminals 4 and 5 and is proportioned to pass only alternating current of 20 cycles per second. It follows that the electromctive forces picked by inductcrs 2 and 3 in response to coded 20 cycle alternating current flowing in the rails is passed by the lter and an alternating electromotive force of 20 cycles coded at the same code rate as the rail current is made to appear across secondary winding i and condenser 0 in multiple.

The adapter AD includes a multiple grid type of electron tube VT in which the functions of an oscillator, a modulator and an amplifier are combined. That is to say, all the functions of devices B. C and D of Fig. l are combined in the electron tube VT. The manner in which the three functions of oscillation, inoculation and amplification occur in a single electron tube is well-known and it need be described in connection with tube VT only as required for a full understanding of my invention. The electron tube VT is an indirect heater type having a gamen f3 plate or anode ID, a cathode II, a filament I2 and five grids I3, I4, I5, I6 and I1.

The adapter AD is provided with three power terminals, designated by the reference characters CO, B32 and B350, to which terminals power is supplied from the corresponding power terminals of the existing train control equipment, and consequently a 32 volt source of direct current exists between terminals B32 and CO and a 350 volt source of direct current exists between terminals B350 and CO. The filament I2 of tube VT is connected across terminals B32 and CO and hence the tube is normally heated and in an active condition. A resistor RI is connected between terminals B35 and CO as will be readily understood by an inspection of Fig. 1 and resistor R'I forms a voltage divider from which there is obtained proper voltages for the different elements of tube VT as will shortly appear.

The secondary winding 1 of transformer TI and condenser 3 are included in a grid circuit which can be traced from grid I4 of tube VT over a condenser 25 and a resistor 26 in multiple, secondary winding 1 and condenser 9 in multiple, a portion of resistor RI to terminal 49 and to cathode II of the tube. Hence the energy of 20 cycles picked up by inductors 2 and 3 and passed by the filter including transformer TI is applied across grid I4 and cathode II of tube VT.

Grids I6 and I1, cathode II, an associated transformer T2, and a tuned circuit comprising winding I8 of transformer T2 and a condenser I3 constitute an oscillation circuit. The parts of this circuit are proportioned so that oscillations of the frequency of 120 cycles per second are produced. Modulation action occurs due to the fact that the potential of the oscillating grids I6 and I1 and the signaling energy applied to grid I4 and cathode II have an effect on the electron stream between anode Ill and cathode II. Due to the placement of the various elements of the tube amplification of the products of modulation is effected in the anode or plate circuit of the tube and which plate circuit eX- tends from power terminal B359 over a portion of resistor RI to a mid terminal 2li, primary winding 2l of a transformer T3, to be referred to later, plate I and intervening tube space to cathode II, mid terminal 43 of resistor RI and a portion of resistor RI to power terminal CO.

Grids I3 and I5 of tube VT are connected in multiple to terminal 26 of resistor RI through a resistor 22 and these grids function as screen grids.

Transformer T3 with its primary and second ary windings 2I and 23, together with a condenser 24, form a filter which corresponds to filter E of Fig. 1 and which filter is tuned sharply at 100 cycles per second so that only the 100 cycle product of modulation created by modulation of the local oscillations by the energy received from the track rails appears across secondary winding 23 of transformer T3 and is applied to the output terminals TC and FT of the adapter. The output terminals TC and FT of adapter AD correspond to the respective input terminals TC and FT of the standard existing train control equipment and to'which input terminals of the standard equipment the train carried inductors 2 and 3 are commonly connected. It is to be seen, therefore, that the 20 cycle coded energy derived from the track rails Ia and Ib of Fig. 1, and applied to the adapter AD, is convert-ed into energy of 100 cycles coded at the corresponding code rate and is applied to the output terminals of the adapter so that standard equipment when connected to such output terminals is effectively operated in response to the 20 cycle rail current.

In order to minimize code distortion at high values of rail current, the condenser-resistor combination comprising condenser 25 and resistor 26 in multiple, is preferably interposed in the connection of secondary winding 1 of transformer TI to grid I4 of tube VT.

Referring to Fig. 3, inductor coils 2 and 3 are mounted on a train in inductive relation to rails Ia and Ib, the same as in Fig. 1, and are connected together so that electromotive forces induced therein due to series rail circuit current are additive. These inductors 2 and 3 are connected to the input terminals 21 and 28 of an adapter indicated as a Whole by the reference character ADI. A. second pair of inductor coils 2a and 3a are mounted on the train in inductive relation to rails Ia and Ib. respectively, and are connected together so that electromotive forces induced therein due to current flowing in a loop rail circuit are additive. Inductors 2a and 3a are connected to input terminals 23 and 30 of adapter ADI. rIn Fig. 3 the trackway apparatus for including the track rails Ia and Ib in both a series rail circuit and a loop rail circuit is not shown for the sake of simplicity, since it would be in accordance with standard practice and forms no part of my invention. For example, such trackway `arrangement for including the track rails in two circuits may be that disclosed in Letters Patent of the United States, Reissue No, 15,830, granted May 6, 1924, to L. V. Lewis, for Railway traffic controlling system. It is sufficient for this application to point out in such track circuit arrangement a single source of a1- ternating current supplies both circuits with current and the two currents are in phase under one traffic condition and are 180 degrees out of phase under another trafc condition. In the instant application it is assumed that alternating current of 20 cycles per second is used for the track circuits.

Since, in Fig. 3, there are two 20 cycle currents n densers 8 and 9 is connected across terminals 21 and 28 of adapter ADI and this filter is tuned to pass only energy of 20 cycles per second, the same as in Fig. 2. Another filter similar in construction is connected to terminals 29 and 30 of adapter ADI and this other filter comprising a, transformer T4 and two condensers 3| and 32 is tuned to pass only energy of 20 cycles per second. 'Ihe adapter ADI includes an electron tube VT of the same construction as the corresponding tube of Fig. 2, and the tube VT of Fig. 3 has its two grids I6 and I1 associated with a tuned circuit arrangement including winding I8 of transformer T2 and condenser I9for generating oscillations of a frequency of cycles per second. The 20 cycle energy passed by the filter including transformer T4 is applied to grid I4 and cathode II of tube VT and consequently amplified products of modulation of the 20 cycle energy mixed with the 120 cycle oscillations are made to appear in the anode circuit of tube VT which circuit is similar to the anode circuit of tube VT of Fig. 2 and need not be again described in detail, eXcept to point out that it includes primary winding 2l of transformer T3. Transformer T3, together with condenser 214, form a filter similar to the corresponding filter of Fig. 2 and which is tuned to pass only energy of 100 cycles so that only the 100 cycle product of modulation appears across the secondary winding 23 of transformer T3 of Fig. 3. Secondary winding 23 of transformer T3 is connected to output terminals 33 and 34 of the adapter ADI and consequently the 20 cycle energy applied to the input terminals 29 and 3@ of the adapter is converted into energy of 100 cycles and applied to the output terminals 33 and 34 ofthe adapter.

Adapter ADI also includes a second electron tube VTI of the indirect heater type and having an anode or plate S, a cathode 36, a filament 3l. and five grids 33, 39, lill, 4I and 42. The lament 3l of tube VTI is connected in series with filament I2 of tube VT across the power terminals B32 and CO of the adapter and consequently both tubes are heated and made active. Electron tube VTi is provided with a grid circuit by which secondary l of transformer Tl is connected across grid ft2 and cathode 3S of the tube, as will be apparent from an inspection of Fig. 3 and hence the 20 cycle energy passed by the filter including transformer TI is applied to tube VTI.

The oscillations derived by the tuned circuit associated with tube VT are applied across grid 40 and cathode 3% of tube VIl through the inductor dll which is coupled to a winding it of transformer T2 of the oscillation circuit. Thus oscillations of 120 cycles per second are applied to tube VTI and modulated by the 20 cycle energy applied to grid t2 from the filter including transformer TI with the result that amplified products of modulation of the 120 cycle oscillations by the 20 cycle energy are made to appear in the anode circuit of tube VTi. This anode circuit can be traced from power terminal B35@ over resistor RI to mid terminal E, a resistor fil, primary winding i8 of a transformer T5, anode 35 and intervening tube space to cathode 36 of tube VTI, terminal i9 of resistor RI and thence to the power terminal CO. The windings 48 and Eil of transformer T with a condenser 5I form a filter which is proportioned to pass only energy of 100 cycles, and hence only the 10Q cycle product of modulation appearing in the anode circuit of tube V'Ill is applied to the output terminals 52 and e3 connected to secondary winding 5d of transformer T5. It follows that the cycle energy derived from the rails by inductors 2 and 3 and applied to the input terminals 2l and 28 of adapter ADi is converted into 160 cycle energy and applied to the output terminals 52 and 53 of the adapter. Since the same source of local oscillation is used for both tubes VT and VTI for modulation by the two 20 cycle currents derived from the rails, the 100 cycle energy applied to the output terminals of the adapter has the same phase relationship as the 20 cycle energy.

The output terminals 52 and 53 of adapter AD@ would be connected to one phase element of the standard train carried train control equipment and the output terminals and 3d of the adapter would be connected to the second phase element of the standard equipment. It is to be seen, therefore, that the standard equipment designed for effecting operation by phase relationship of two 10G cycle currents would be effectively operated by the phase relationship of the two 20 cycle currents derived from the track rails and applied to the adapter ADI of Fig. 3.

It is to be seen, therefore, that I have provided railway traffic controlling apparatus incorporating novel means which can be connected between the present train carried inductors and the existing train carried train control equipment and such standard train control equipment which is designed for effective operation by energy of l0() cycles per second can be effectively operated by energy of 20 cycles per second supplied to the track rails.

Although I have herein shown and described only two forms of railway trafc controlling apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

l. In railway traffic controlling apparatus for use with train carried train control equipment effectively operated by alternating current of a preselected first frequency when alternating current of a preselected second frequency is supplied to the rails to induce energy of said second frequency in inductors mounted on the train, the combination comprising; an adapter including a first and a second filter, an oscillator and a modulator; said first lter having input terminals to which said inductors are connected and output terminals connected to the input side of said modulator and proportioned to pass only energy of said second frequency, said oscillator connected to the input side of the modulator and adaptable of delivering oscillations of a frequency which when modulated by the energy passed by said first filter produce as a product of modulation energy of said first frequency, said second lter having input terminals connected to said modulator and proportioned to pass only said energy of said first frequency, and output terminals for said second filter adaptable of connection to said train control equipment.

2. In railway traffic controlling apparatus for use with train carried train control equipment effectively operated by alternating current of a preselected iirst frequency when alternating current of a preselected second frequency is supplied to the rails to induce energy of said second frequency in inductors mounted on the train, the combination comprising; an adapter including a first and a second filter, an oscillator, a modulator., input terminals for connection to said inductors and output terminals for connection to said train control equipment; said first nlter interposed between said input terminals and said modulator and adapted to pass only energy of said second frequency, said oscillator connected te said modulator and adapted to supply oscillations of a predetermined frequency to produce when modulated by the energy passed by the first lter energy of said first frequency, and said second filter interposed between said modulator and said output terminals and adapted to pass only energy of said first frequency.

In railway traffic controlling apparatus for use with train carried train control equipment responsive to alternating current of a preselected relatively high frequency applied thereto through the medium of a receiver, the combination comprising; an adapter including a rst and a second filter, an oscillator and a modulator; said first filter connected between said receiver use with train carried train control equipment effectively operated by alternating current of a preselected first frequency when alternating current of a second preselected frequency is supplied to the rails to induce energy of said second frequency in inductors mounted on the train, the combination comprising; an adapter having input terminals connected to said inductors and output terminals connected to said train control equipment and including a modulator, an oscillator and a filter; said oscillator connected to said modulator and effective to supply oscillations which when mixed with said energy of said second frequency received through said inductors produce as one product of modulation energy of said first frequency, and said filter interposed between the modulator and said output terminals and proportioned to pass only said one product of modulation to effectively operate said train control equipment in response to the alternating current of said second frequency derived from the rails.

5. In railway traffic controlling apparatus for use with train carried train control equipment effectively operated by alternating current of a preselected first frequency when alternating current of a preselected second frequency is supplied to the rails to induce current of said second frequency in inductors mounted on the train, the combination comprising; a train carried electron tube having an anode, a cathode and a plurality of grids; means including a first filter to connect said inductors to a first grid and cath-ode of said tube to apply the alternating current of said second frequency to the tube, an anode circuit for said tube, :means including a tuned circuit connected to at least a second grid and the cathode of said tube to apply to the tube oscillations of a frequency which when modulated by said second frequency produce in the anode circuit of the tube energy of said first frequency, a second filter effective to pass only energy of said first frequency, and means including said second lter to couple said anode circuit to said train control equipment to effectively operate the train control equipment in response to the current of said second frequency picked up from the rails.

6. In railway traffic controlling apparatus for use with train carried train control equipment effectively operated by alternating current of a preselected iirst frequency when alternating current of a preselected second frequency is supplied to the rails to induce energy of such second frequency in inductors mounted on the train in inductive relation to the rails, the combination comprising; an electron tube having an anode, a cathode and at least two grids; a first filter adapted to pass only energy of said second frequency, means including said first filter to connect the inductors across one of the grids and cathode of said tube, an anode circuit for the tube, means including a tuned circuit connected across the other grid and cathode of the tube to create oscillations of a frequency which when modulated by said second frequency energy produce in the anode circuit energy of said first frequency amplified by the action of said tube, a second filter adapted to pass only energy of said first frequency, and means including said second filter to couple the anode circuit to said train control equipment to effectively operate such equipment in response to the alternating current of said second frequency picked up from the rails.

7. In railway trafiic controlling apparatus for use with train carried train control equipment effectively operated by 100 cycle alternating current When cycle alternating current is supplied to the rails to induce in a train carried receiver an alternating electromotive force of a frequency of 20 cycles, the combination comprising, an adapter including a first and a second filter and a multiple grid electron tube and said adapter provided with input terminals for` connection to said receiver and output terminals for connection to said train control equipment, said first filter adapted to pass a 20 cycle electromotive force and connected between said input terminals and a selected grid and cathode of said tube, means including a tuned circuit connected to a selected pair of grids and the cathode of said tube to produce oscillations of 120 cycles per second and which oscillations are modulated by said 2l0 cycle electromotive force to produce in the anode circuit of the tube energy of cycles per second amplied by the action of the tube, and said second filter interposed between said anode circuit and said output terminals and adapted to pass only 100 cycle energy for effective operation of said train control equipment in response to the 20 cycle alternating current picked up from the rails.

8. In railway traffic controlling apparatus for use with train control equipment effectively operated according to the phase relationship of two alternating currents of a preselected first frequency supplied to two phase elements when two alternating currents of a preselected second frequency are supplied to a series and a loop rail circuit to induce electromotive forces in two respective inductors mounted on the train; the combination comprising, an adapter having input terminals for connection to each of said inductors and output terminals for connection to each of said two` phase elements and including two frequency converting channels, each of said channels comprising a first and a second filter and a modulater, each of said first filters connected between selected ones of the input terminals and the associated modulator and adapted to pass only an electromotive force of said second frequency, each said second lters connected between the associated modulator and selected ones of said output terminals and adapted to pass only energy of said first frequency, and a local source of oscillations for said adapter connected to each of said modulators and effective to supply oscillations of a frequency which when modulated by electromotive force of said second frequency produce as one product of modulation energy of said first frequency.

9. In railway traffic controlling apparatus for use with train control equipment effectively operated according to the phase relationship of two alternating currents of a preselected first frequency supplied to two phase elements when two alternating currents of a preselected second frequency are supplied to a series and a loop rail circuit to induce electromotive forces in two respective inductors mounted on the train; the combination comprising, an adapter having input terminals for connection to each of said inductors and output terminals for connection to each of said two phase elements and including two frequency converting channels, each of said channels comprising a rst and a second lter and an electron tube; each of said tubes provided with an anode, a cathode and a plurality of grids; an anode circuit for each of said tubes, a tuned circuit arrangement connected to selected ones of the grids and cathode of a selected one of the tubes to produce oscillations, circuit means coupled to said tuned circuit and connected between a grid and the cathode of the other tube to apply said oscillations to said other tube, eachsaid rst filters connected between selected ones of the input terminals and a grid and cathode of the associated tube and adapted to pass only electromotive force of said second frequency to modulate the oscillations applied to that tube, each said second iilter interposed between the anode circuit of the associated tube and selected ones of the output terminals and adapted to pass only energy of said rst frequency, and said tuned circuit arrangement effective to create oscillations of a frequency which when modulated by electromotive force of said second frequency produce as one product of modulation energy of said rst frequency.

RALPH K. CROOKS. 

